The resource admission and control sub-system proposed by ETSI TISPAN relates to bearer control layer. It implements policy control, resource reservation, admission control as well as accessing, convergence, and translation of network address port/protocol of the core network. The framework of resource admission and control subsystem is illustrated in FIG. 1.
In FIG. 1, RACS refers to resource admission and control sub-system which includes RACS-related function units such as a service-based policy decision function (SPDF) unit, an access-unction (A-RACF) unit, an application function (AF) unit, a network attachment sub-system (NASS), an access node (AN), a resource control enforcement function (RCEF) unit, and a border gateway function (BGF) unit, etc.
The RACS is a subsystem for implementing policy control, resource reservation, and admission control. The RACS further provides supports for the control of Network Address Translation (NAT) in the BGF. The RACS provides a policy-based transmission control service for the application layer. With the RACS, the application layer accomplishes admission control, application, and reservation of the bearer resources within the coverage of the application layer.
The SPDF provides below functions:
checking to see if the information in the request from the AF is consistent with the local policy rules defined by the SPDF;
authorizing the resources requested by the AF session. The SPDF utilizes the information in the request from the AF to compute appropriate authorization. (e.g., compute the number of media components which need to be authorized);
determining the location of BGF and/or A-RACF according to the requested transmission capability;
requesting A-RACF resource;
requesting services from the BGF. These services include opening/closing gate control, marking the packet, allocating resource based on flow, NAT, hosted NAT transversal, setting up uplink and downlink service policy, measuring service, etc.;
concealing internal details of RACS from the AF;
concealing details of transport layer from the AF;
mapping the resource request of AF to the request for the A-RACF and/or BGF.
The A-RACF includes below functions of: admission control; and network layer policy assembly.
In 3GPP R7, the service based local policy (SBLP) and flow based charging (FBC) in 3GPP R6 are combined into a policy and charging control (PCC) scheme, as illustrated in FIG. 2, in which:
The functions related to the policy control in PCC include:
“gate control” function: enable or disable the packet passing capability of service data flows (SDF). No matter the charging control and policy control functions have or have not been applied, the “gate control” function can be applied to a session.
Session event: The capability of notifying the application layer events and reacting to the application layer events may trigger new user level behavior. The session events capability is a necessity for the application of gate control function. For instance, in the gate control function, the session termination event may trigger a corresponding packet disable behavior.
Quality of Service (QoS) authorization function: Authorized QoS refers to a maximum QoS authorization for some IP flows. When multiple IP flows exist in one bearer, the authorized QoS for these flows may be combined together as the authorized QoS for the bearer. Subscription information relating to QoS may be used to assist the specific QoS authorization operation, including acceptation, rejection or modification.
QoS execution function: The QoS execution function of policy and charging control (PCC) must be consistent with the function of PEP in the service based local policy (SBLP). The QoS execution function includes degrading processing of the requested bearer QoS performed by the gateway (GW) when establishing the bearer. The policy and charging rules function (PCRF) may also actively provide authorized QoS information for the GW through Gx+ reference point according to some triggering condition and enable the GW for execution.
The Charging related functions include:
charging association: support for charging association between the application layer charging and the bearer layer charging.
charging control: IP flow is identified in accordance with the charging rule and a corresponding charging operation is performed. Related subscription information should also be taken into consideration in the process. The charging rule in the new PCC may be provided by PCRF dynamically or may be pre-configured in the GW.
According to prior art, the implementation of SPDF function entity relating to TISPAN RACS specification and the implementation of PCRF function entity relating to 3GPP PCC specification have already been provided. Both the implementations of SPDF and PCRF need to provide interfaces for the application layer function AF. The AF requests resources from the bearer control layer through the interfaces.
In RACS specification, the interface between SPDF and AF is Gq′ interface. The message type relating to the interface includes: Authorization Authentication Request, AA-Request (AAR)/Authorization Authentication Answer, AA-Answer (AAA), re-authentication and/or re-authorization Request (RAR)/re-authentication and/or authorization answer (RAA), Session-Termination-Request (STR)/Session-Termination-Answer (STA), Abort-Session-Request (ASR)/Abort-Session-Answer (ASA). All the messages for one session have a same <Session-Id>,<Session-Id> to identify the same session.
For the Gq′ interface, the format of AAR message is defined as (ETSI TS 183 017):
<AA-Request> ::= < Diameter Header: 265, REQ, PXY >        < Session-Id >        { Auth-Application-Id }        { Origin-Host } (origin host)        { Origin-Realm }        { Destination-Realm }        *[ Media-Component-Description ]         *[ Flow-Grouping ]        [ AF-Charging-Identifier ]        [ SIP-Forking-Indication ]        *[ Specific-Action ]        [ User-Name ]        [ Binding-Information ]        [ Latching-Indication ]        [ Reservation-Priority ]        [ Globally-Unique-Address ]        [ Authorization-Lifetime ]        *[ Proxy-Info ]        *[ Route-Record ]        *[ AVP ]  ( other attribute-value pair)
In PCC scheme, the interface between PCRF and AF is Rx interface. The message type relating to the interface includes: AAR/AAA, RAR/RAA, STR/STA, ASR/ASA. All the messages for one session have a same <Session-Id>,<Session-Id> to identify the same session.
The message format for Rx interface is defined as (3GPP TS 29.214):
<AA-Request> ::= < Diameter Header: 265, REQ, PXY >        < Session-Id >        { Auth-Application-Id }        { Origin-Host }        { Origin-Realm }        { Destination-Realm }        *[ Media-Component-Description ]         *[ Flow-Grouping ]        [ AF-Charging-Identifier ]        [ SIP-Forking-Indication ]        *[ Specific-Action ]        *[ Subscription-ID ]        *[ Proxy-Info ]        *[ Route-Record ]        *[ AVP ]  ( other attribute-value pair )
The fixed-mobile convergence (FMC) application includes xDSL fixed access as well as a variety of mobile access schemes such as UMTS RAN access, WiMAX access, W-LAN access. According to the existing ways of implementation, SPDF function entity is needed to support the resource admission and control in fixed access mode. PCRF is also needed to support the resource admission and control in mobile access mode. However, using two sets of bearer control layer entities is not conducive to the construction and maintenance of the network, and not conducive for the AF to implement bearer control, neither.